public class EncryptAndDecrypt {
	String encrypt(String sourceString,String password){
		char [] p =password.toCharArray();
		int n=p.length;
		char [] c =sourceString.toCharArray();
		int m = c.length;
		for(int k=0;k<m;k++) {
			int mima =c[k]+p[k%n];
			c[k] = (char)mima;
		}
		return new String(c);
	}
	String decrypt(String sourceString,String password) {
		char [] p =password.toCharArray();
		int n = p.length;
		char [] c = sourceString.toCharArray();
       int m = c.length;
       for(int k=0;k<m;k++){
           int mima=c[k]-p[k%n];       //解密
           c[k]=(char)mima;
       }
       return new String(c);    //返回明文
   }
}
